1. Field of the Invention
The present invention relates generally to a technique for estimating a direction of travel of a pedestrian using a portable terminal device.
2. Description of the Background Art
A technique has been proposed which can estimate a direction of travel of a pedestrian in a portable terminal device that has a high freedom of posture. Especially, an application for observing the movement locus of the pedestrian by making the pedestrian bring that portable terminal device therewith (PDR: Pedestrian Dead Reckoning) has been known, for example. In such an application, it is necessary to identify the direction of travel of the pedestrian.
The technique described in JP 2003-302419 (A), however, assumes that the terminal device keeps a posture that is one while the device is at a standstill, even during a walking movement, although the terminal device has a high freedom of posture. Thus, this technique has a problem of poor practicality. Moreover, in this technique, data of a sensor is directly analyzed and therefore there is a problem that this technique is sensitive to a noise. Furthermore, in this technique, acceleration data is sequentially held and therefore there is a problem of lack of portability.
In addition, the technique described in JP 2008-116315 (A) performs statistical operation for a plurality of walking steps and therefore has a problem of poor responsiveness.
Moreover, the techniques described in JP 2006-104140 (A), JP 2012-145457 (A), and JP 2012-242179 (A) require frequency conversion, autocorrelation processing, and the like and therefore have a problem of a large calculation amount.
Furthermore, in the technique described in JP 2012-168004 (A), there is a problem that, although a swinging phase and a standing phase have to be defined, it is difficult to clearly define them and therefore erroneous detection occurs frequently.